GN: Fix support errorprone and java_binary

GN: Fix support errorprone and java_binary

Also adds errorprone to the default set of targets.

BUG=509156
Committed: https://crrev.com/40ba686a6a6cd4387759376bebe505298742ca50
Cr-Commit-Position: refs/heads/master@{#338803}

[agrieve, 2015-07-11 02:19:54]

agrieve@chromium.org changed reviewers:
+ brettw@chromium.org, cjhopman@chromium.org

[agrieve, 2015-07-11 02:19:54]

cjhopman@chromium.org: Please review changes in everything

brettw@chromium.org: Please review changes in /BUILD.gn

[brettw, 2015-07-11 17:14:02]

toplevel BUILD.gn lgtm

[cjhopman, 2015-07-14 18:21:34]

lgtm

[agrieve, 2015-07-14 18:27:52]

The CQ bit was checked by agrieve@chromium.org

[commit-bot: I haz the power, 2015-07-14 18:28:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1233453010/1

[commit-bot: I haz the power, 2015-07-14 18:35:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-14 18:35:07]

Try jobs failed on following builders:
  linux_chromium_gn_chromeos_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_gn_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_gn_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  win8_chromium_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_ng/...)

(exceeded global retry quota)

[agrieve, 2015-07-15 00:44:37]

The CQ bit was checked by agrieve@chromium.org

[agrieve, 2015-07-15 00:44:38]

The patchset sent to the CQ was uploaded after l-g-t-m from
cjhopman@chromium.org, brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1233453010/#ps20001
(title: "Add errorprone target only for OS=android")

[commit-bot: I haz the power, 2015-07-15 00:45:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1233453010/20001

[commit-bot: I haz the power, 2015-07-15 02:09:24]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-15 02:11:04]

Patchset 2 (id:??) landed as
https://crrev.com/40ba686a6a6cd4387759376bebe505298742ca50
Cr-Commit-Position: refs/heads/master@{#338803}